


In Which Alphys and Mettaton Do It, But Like, Just as Friends

by obstreperose



Category: Undertale (Video Game)
Genre: Cunnilingus, F/M, Friends With Benefits, Guy With Vagina, Oral Sex, Robot Kink, Scent Kink, Sweat, Tribadism
Language: English
Status: Completed
Published: 2016-01-08
Updated: 2016-01-08
Packaged: 2018-05-12 14:13:27
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,860
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/5668912
Author URL: https://archiveofourown.org/users/obstreperose/pseuds/obstreperose
Summary: <blockquote class="userstuff">
              <p>In this one, Alphys and Mettaton do it, but like, just as friends.</p>
            </blockquote>





	In Which Alphys and Mettaton Do It, But Like, Just as Friends

Alphys brushed the back of one paw over her brow, thick, claw-tipped fingers flexing reactively as she shook them out of the cramp from moving the couch. The scene: an almost enshrinement of her main viewscreen, a still-mostly-okay sofa dragged out from storage to sit in front of it. The automatic door whirred smoothly closed in the wake of the couch’s rear arm. A long wire connected the viewscreen’s rear port to the tower of her computer, sitting stolid and slightly yanked over atop her desk. Therein lay a bounty, a multiplicitude of bounties, of anime. The whole operation seemed to point towards the inevitable conclusion that the anime would be coming out of the computer, onto the viewscreen, and into the hearts of those sitting on the salvaged couch. It was, in a way, seamless.

Mettaton, of course, hadn’t helped at all. He swept the back of one white-gloved hand (misnomer: it was really just a glove affixed to a hidden metal stump) through his synthetic hair, which seemed to shimmer reactively in the sterile light, as he stood watching Dr. Alphys clap her hands to her knees, winded.

“There,” she said, her soft, raspy voice, sucking in a bit of breath, and stood up straighter, fanning her labcoat around the collar, letting air touch her scaly skin. She looked up at her friend, engaged a toothy smile. “Are you ready?”

“As I’ll ever be, darling.” He smiled back, his mouth (and most of his face) flexible silicone, rather softer than the rest of his daring-though-imposing body. Mettaton’s voice had a definite lilt, but internal speakers made it into a deep basso, vibrating in a rhythmic pulse. Just talking to him was a kind of performance. “What are we serenading ourselves with this time?”

Alphys brandished the empty case: the scratched-up DVD inside was residing snugly in the tower’s tray. “ _Telltale Spirits RE-Wind Witch Club_. It’s meant to be very, um…moving!”

“Who told you that? Didn’t you find it in the garbage?” He sashayed over to the sofa, affixing his hands to the back cushions and doing a seamless overhead rotation - _fwoomp_ \- into his seat. His arms, ringed with chromey-smooth corrugation, slinked neatly to his sides. One leg crossed neatly over the other, the pose of the perfect _conoisseur_. It was not that Mettaton liked anime. He just felt that you should appear physically refined when in the process of receiving an entertainment, howsoever dire.  

Alphys coloured. “Well, um…the back of the box. But they’re usually right! I almost always feel just the same way as they said I would about the anime after I’ve watched it!”

“That’s because you’re suggestible, Alphys dear,” he said cattily, patting the cushions beside him. The instant Alphys hefted her weight into the seat - having to lift herself up backwards on her palms, with some struggle around the issue of her tail - he abandoned his prior resolution to refinement and brought his considerable legs up, smooth black vinyl casing of his thighs glinting beautifully in the overhead light as he adopted a sort of sideways kneel, back flexing with a soft theatrical gasp against the couch.

“I am not,” she said steadfastly, quite capable of standing up to her best friend after all this time. “ _You’re_ too cynical. You don’t believe in the transformative magic of anime.” She glanced around for the remote, for the moment not finding it. Ah well. She needed to get comfortable anyway.

“I am affronted at the spurious notion that a single resonating strand of cynicism exists within me,” he said back, lifting a glove melodramatically to his brow, as if he was about to manufacture a fainting fit. All a joke, of course. Alphys and Mettaton had a well-understood interplay by now. He eased his glove back, pattering the fingers along his vinyl thigh, material contrast. “It’s just that anime is useless and dull. Except insofar as it relates to human history, which I’m beginning to think might be _very_ slightly.”

“I got the idea for your original chassis from an anime,” said Alphys with a sly, toothy grin. “ _Sixbuster Gun Rectangle_.” Her face became momentarily worried. “I mean, I left out the guns, of course. Those things look very dangerous! Not to mention impractical. And of course they spell Gun Rectangle’s end when he overloads his gun core to fire a _meteor resonance salvo_ at Queen - “

“You didn’t want that to happen to me?” interrupted Mettaton, eager for an opportunity to make dramatic hay. He leaned into her, the vibrations of his chest subwoofer sending a deep shake through the couch and, in turn, the Royal Scientist’s chubby body. “Oh, Alphys! You are sweet! To think - “ He reclined dramatically at a near one hundred and eighty degree angle, crossing his arm across his chest as if struck fatally by fortune’s arrows. “A ‘guns’ could have undone me, were it not for the sparkling brilliance of your foresight!”

Alphys giggled, a chuffing, snickering sound, and clambered over him herself, one soft palm running over the metal casing of his chest, feeling the vibrations produced in amplitude by her friend’s dramatics. She was lightly sweaty from dragging the couch into position, not to mention the constant heat of the lab, positioned as it was in Hotland and running as it did so many high-yield electronics. She also hadn’t showered in a little while. She didn’t think Mettaton would mind: he had no sense of smell.

“It’s so easy with you,” she said, and he whirled one arm up, the snakey chrome of it pressing enfolding against her back. His silicone lips formed a grin. They were just friends - but sometimes, she was right, it was very easy to find the place and time to blow off a little steam. The hunt for the remote withered on the vine: in a moment, their night together had become something else. Even before she’d made a body for him, of course, there had been moments…these had occasioned a few whispers in her ear, months later, as she tinkered with his body-upgrade parts.

“I aim to please, darling,” he said loftily, and softed his lips against the crest of scales near the top of her head, pulling her close to him with an easy candour that was still more friendly than romantic. Mettaton had sensation: he could feel the kiss, the rough-soft texture of Alphys’ scales, and pick up on the warmth in her skin that resolved into an ochre flush a handful of seconds later. “Are we released from anime’s tyranny, for the time being?” His hand dappled naughtily around her tail, running its length and then sliding down to flirt up the tails of her labcoat, exposing her bare, wide thighs. “Oh, please, do say yes.”

“I think a short period of recusement from anime would be acceptable,” said Alphys stuffily, trying to mimic the floweriness of her friend’s phrasing and falling a little short. Still, they both giggled at the attempt: pressed their foreheads into each other, Alphys’ scales tickled by Mettaton’s glimmery-black synthetic hair.

It had taken some experimentation, at first, to figure out where to touch him to occasion pleasure. Alphys had designed him with certain ‘soft spots’, around the hips, the thighs, where a finger-touch should feel at once more subtle and more intense than other-where…but Mettaton was very much an individual, and the ways he had of adapting to his new body and making it distinct to him continued to surprise her. So it was that she found herself rubbing soft, lightly sweaty fingers up against the junction of his neck to his chestpiece, where ring-lined chrome centred the motivating actuators of every other joint in his body.

Mettaton moaned airily, as much performance as pleasure - but then half of the enjoyment he took out of these encouraged liaisons was the gentle drama of them, the rise and eddy of heat and emotions. Alphys’ body was an intuitive surface against which his own could flex. And it wasn’t as though her touches there _weren’t_ making his leg jolt in stimulated delight…

“Um, you like that, huh?” she said, her voice halting and grainy, but fond, warm, close. He snickered, softly.

“I do.“ He was past sarcasm now - or, not quite. “Oh, Alphys, I adore it. Your supple fingers make art of me!”

Her thighs parted, straddled his waist. He could feel the soft fabric of her panties skating over the metal heart insignia he wore there as she found her equilibrium: feel too the heat beneath them, the plush mound of her vulva, the homogeneous curve of her rump.

“Oh Alphys, dear, let’s do get undressed,” he said, with a soft vamp quite as unto the movies. She rolled her eyes: of course he _had_ nothing to undress. He did own a feather boa, purchased by her as a gift, which he would occasionally don only so that he could throw it off dramatically. Alphys shrugged out of her labcoat and reflected that perhaps the boa would have to make an appearance in the next of these sessions, if only so that they were on slightly more even footing clothes-wise.

She peeled out of the slight, clinging undershirt she wore beneath her coat, its armpits darkened gently with sweat, and then her small, round-bottomed breasts were bare and her belly too and her distinct smell, musky and feminine and a little bit perpetually sexually insurgent, just her here alone with the scent of herself and Mettaton. She leaned into him and planted a pressed-mouth kiss against his cheek, the silicone side, not that with the exposed metal. He flexed reactively and a soft shudder of simulated breath passed his moulded lips.

“You’re a handful,” she said, with the tone of a one-shot verdict, and ran her stubby fingers up through his hair, tossing it back from his brow, thumb stroking at the delicate arrangement of the hairline.

“Oh, don’t go hard on me.” His lips danced up in an ecstatic smile. “I’m at least two.” She snickered softly and drew back on her knees a little, bare belly wobbling, so that she could reach down a hand and stroke herself to the tops of his thighs, feeling their vinyl warmth, the way they flexed and rippled under her palm’s pressure, not rigid like his chest but pliant, soft, cushioned. She could sink her face against them: did, and brushed a breathing kiss there.

“I’m wearing the inverse attachment tonight,” he said devilishly, tapping once with a glove-finger at the control panel on his chest. “It’s commonly considered bad form to match, I believe, but since we are _alone_ \- “

Alphys watched as the hidden plating around his crotch slipped away, and then in the midst of black thighs, cushioned touch-skimming softness, there was his sex for the moment: artfully crafted inner labia, outer labia slim and soft, a bead-like clitoris cresting the top, already softly slicking with organic lubricants from his inner reservoir.

“You _were_ ready for me,” she said, and stroked a finger against him, short, curling in the natural shape of her grip, gathering up slickness and wondering at how he managed to feel so - not realistic, that was the wrong word, but attached to himself, how good he was at being without artifice. She had certainly only done about half of it. The rest of it was all Mettaton.

He lifted his lips in a jouissant smile. “Oh, what can I say? Once you’re this close to me, I can hardly resist your allure!”

She snorted happily, laughed it off. “No way. You just wanted to try out your new toy!”

“I might be a little guilty of that too,” he said, glancing audaciously to one side. “But who’d convict me? It’s so wonderfully made! I barely dare to experiment with it myself!”

Alphys leaned in, dappling her tongue with only slight clumsiness up the centre of his sex, and felt a soft happy sense of one-upsmanship as his words melted into moans, much more genuine than forced this time. Her mouth affixed on him, slim barely-there lips pressing to either side of her tongue and creating suction around its travail up his pussy’s warm centre ground, her fingers easing in beneath and teasing, pressing pads flat, at the delta of his perineum, clad in black but flexing and sensitive beneath. Mettaton’s thighs flexed and toes pointed elegantly down, parted around Alphys’ weight at a divatic splay. “ _Oh_!”

That’s what I thought!, thought Alphys, smugly, and dropped a hand to ease down her own panties, feeling suddenly airless and too-tightly trapped beneath them. The slick warmth of her pussy clung against her thighs as the stem on her heat was removed: she was copious, hot with warm-wet desire, and she meant to get her fill of it tonight.

Against him, her tongue lashed up in delicate apportions, tip flexing neatly under the curlature of his clit, fitted with a buzzer that sent electric stimulation all through his body, made his articulation points flex and tense in heady heat. Putty in my hands, thought the Royal Scientist, self-satisfiedly, and would have spoken it if she hadn’t been very engaged with her mouth.

She lifted up, her mouth dripping with Mettaton’s lubricant - it tasted sweet and sharp - and clambered up atop him, joining her own sex quite dominantly to his, organic against synthetic, hers a little plusher, fuller, heavier, his more delicate and fine-tuned. Alphys ground out her pleasure against him in slow, humping thrusts, paws settling on the dial on his chest, playing over the vents of his subwoofer as his breath modulated frantically up and down, wildly back-forth. It made him vibrate thrillingly, all over the body: she leaned forward so that her breasts pressed just slightly against his chest, the hard metal surface, its chrome now misted with her sweat.

Her own hand slipped down between her legs, assisting the tribadism with frantic self-stimulation that could not help but brush and jolt against Mettaton too. Fingers dragged up between the plush, swollen lips of her vulva, barely glancing at the warmth-wetness between, her entrance plumbed usually only by them and by small toys she kept scattered on her desk. She tensed her teeth and ground a groaning _hmph_ of pleasure between them, the first joints of her fingers easing against the heavy hood of her clit, barely suggesting their touch on it, still enough to make her sink against Mettaton and work her sweat-raddled thighs, pushing and slicking her sex, sloppy with his lube and screaming for persistent stimulation, against his fine-lipped vulva, now all strewn and astray. He, ballerina-esque, lifted and pumped his hips with pouting shivers of his lips up against her.

“Fingers,” she panted, “now,” and his cording arms slipped down - shakily, their course charted with bumps from the constant shiver of electric stimulation he was receiving - ‘till those smooth gloves could join her own hands, one long, thick digit sliding up synthetic-slick and machine-hot against the delta of her sex, from bottom to top and then working itself delicately in - and Alphys flexed against him in near-orgasm, her face screwing up into an incredibly undignified heat-tense. “Ah!”

Her own hand, in return, nearly separated their tribadism with how lavishly it ran over his shivering sex, his inner lips parted by her short fingers, which now plumbed in, reciprocating headily and intensely to the full extent of their depth. He tensed - moaned - needed something longer, but Alphys would do - and fell against her at the exact moment that she fell, sweat-wreathed and panting, hips tensing, against him.

“ _Nnnh_.” Hard to say which set of lips it had come from. She pushed herself up from where she’d collapsed on Mettaton’s chest - her skin sticking to him with heat and dampness - and threw herself back on the couch, tail curling up behind her, cheeks in an ochre flush, body stimulated and alive.

Mettaton fanned himself lazily, his own cheeks executing their flush routine - an autonomous thing outside his control, which was quite telling of his temperament in this case. “Well. That was certainly an interesting experiment.”

“Mh-hm.”

“You’re supposed to say,” he said, airily, sitting up, composing himself. One arm extended along the back of the couch and his gloved fingers stroked at the flared scales around the top of her head, a grooming act that the doctor found very relaxing, “‘that’s my speciality’, or something in that vein. Really, Alphys, don’t you _ever_ watch my show!”

“Always, you know that,” she said, chuffing at him lightly, hunting along the arms of the couch for her glasses. They had been lost at some point in the impromptu sexual scuffle.

“Well, on _television_ ,” he said, pretending to be affronted, “or in the _the-ah-ter_ , people exercise wit.” He turned and grinned at her: unmanufactured, for a second, just Mettaton, her friend, overjoyed to exist in the body that she had built and he inhabited.

“In anime too,” said Alphys, with a devious wiggling of her brow ridges. She flourished the remote: it had fallen between the couch cushions. “Shall we get down to it?”

Mettaton groaned, but acquiesced companionably.

**Author's Note:**

> I hope you enjoyed this very smutty story! If you did, you can find more of my writing at obstreperose.tumblr.com. I take requests of all kinds, and would love to hear all your no doubt wonderful prompts!


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